Which laboratory test can indicate the functionality of the kidneys?

The blood urea nitrogen (BUN) test is a crucial laboratory test that assesses kidney functionality by measuring the amount of urea nitrogen in the blood. Urea is a waste product formed from the breakdown of protein and is normally eliminated from the bloodstream by the kidneys. When kidney function is impaired, urea nitrogen levels can rise, indicating that the kidneys are not effectively filtering waste from the blood.

The BUN test provides insights into how well the kidneys are performing their excretory function; elevated levels may suggest kidney disease, dehydration, or other conditions affecting renal capacity. This makes it a valuable tool in veterinary and human medicine for monitoring kidney health.

Other options, while relevant in different contexts, do not primarily measure kidney function. The bilirubin test is used to evaluate liver function and assess conditions like jaundice. The ALT test primarily evaluates liver health and is not indicative of kidney functionality. The culture and sensitivity test is designed to identify bacterial infections and assess the effectiveness of antibiotics, focusing on infection rather than kidney function.